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What happens to an atom that has a positive charge?
- A. Gained an electron.
- B. Lost an electron.
- C. Gained a proton.
- D. Lost a proton.
Correct Answer: B
Rationale: When an atom has a positive charge, it means it has lost one or more electrons. Electrons carry a negative charge, so the loss of an electron results in the atom becoming positively charged. Therefore, the correct answer is B: Lost an electron.
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What volume of silver will weigh exactly 2500.0 g? The density of silver is 10.5 g/cm³.
- A. 262.50 cm³
- B. 238.1 cm³
- C. 0.0042 cm³
- D. None of the above
Correct Answer: B
Rationale: To find the volume of silver, we use the formula: Volume = Mass / Density. Plugging in the given values, Volume = 2500.0 g / 10.5 g/cm³ = 238.1 cm³. Therefore, the correct answer is 238.1 cm³, which corresponds to option B.
What can be predicted by using the periodic table?
- A. The properties of each of the elements
- B. The charges of polyatomic ions
- C. The number of isotopes in each element
- D. The potential for the discovery of new elements
Correct Answer: A
Rationale: The periodic table is a fundamental tool in chemistry that organizes elements based on their properties. By using the periodic table, scientists can predict the properties of each element. The arrangement of elements in the table groups together elements with similar characteristics, allowing for the prediction of various properties such as reactivity, atomic size, and electronegativity. These predictions are possible because elements in the same group or period exhibit similar chemical behaviors. Therefore, the correct answer is A: The properties of each of the elements.
Which type of reaction is exemplified by the chemical equation Cr + Fe(NOÄ‚�)Ä‚‚ Ć’ Fe + Cr(NOÄ‚�)Ä‚�?
- A. Single replacement
- B. Decomposition
- C. Double replacement
- D. Combustion
Correct Answer: A
Rationale: The given chemical equation represents a single replacement reaction. In this type of reaction, one element displaces another element in a compound. In the provided equation, chromium (Cr) replaces iron (Fe) in the compound Fe(NOÄ‚�)Ä‚‚, resulting in the formation of Fe and Cr(NOÄ‚�)Ä‚�. Single replacement reactions involve the substitution of one element for another in a compound, which is precisely demonstrated in this scenario. Therefore, the correct classification for this reaction is a single replacement reaction.
What is the name for a reaction in which electrons are transferred from one atom to another?
- A. combustion reaction
- B. synthesis reaction
- C. redox reaction
- D. double-displacement reaction
Correct Answer: C
Rationale: A redox reaction, also known as a reduction-oxidation reaction, involves the transfer of electrons from one substance to another. During this process, one substance is oxidized (loses electrons) while another is reduced (gains electrons). This transfer of electrons is a key characteristic of redox reactions, making choice C the correct answer. Combustion reaction (choice A) involves a substance reacting with oxygen to produce heat and light, but it does not necessarily involve electron transfer. Synthesis reaction (choice B) involves the combination of two or more substances to form a new compound, without necessarily involving electron transfer. Double-displacement reaction (choice D) involves the exchange of ions between two compounds, but not the transfer of electrons from one atom to another.
A carbon atom with fewer neutrons than a neutral carbon atom is known as what?
- A. Isotope
- B. Ion
- C. Both are correct
- D. None of the above
Correct Answer: A
Rationale: The correct answer is 'Isotope.' An isotope is a variant of a chemical element that has the same number of protons but a different number of neutrons in its nucleus. In this scenario, a carbon atom with fewer neutrons than a neutral carbon atom represents a different isotope of carbon with a distinct atomic mass. The difference in neutron count does not alter the atom's charge, ruling out the possibility of it being an ion. Therefore, the appropriate term to describe this situation is 'Isotope.'